In recent years there has been a gaining effort to establish a so-called "cashless society". One aspect of that effort has involved a steady increase in the use of personal devices, usually in the form of cards, to authorize or support various significant transactions. For example, cards are widely used in the forms of identification cards or transaction cards, specifically employed for credit cards, debit cards, cash cards, value cards, banking cards and so on. Classifications and standard definitions of such cards are sometimes ambiguous and volatile.
Although various card structures have been proposed in the past, along with various forms of processing systems, a need continues to exist for a reliable, economical, and practical transaction card along with similarly effective systems for producing such cards and regulating their use.
Many forms of transaction cards are used in environments where some opportunity exists to visually inspect the cards as they are used. For such applications, the requirements of a so-called non-counterfeitable card are rather different than those applications for such a card where there is no opportunity for visual inspection, as in the case of automatic teller machines. Essentially, fraudulent cards are easier to use if the counterfeit need not pass a visual inspection. Consequently, in applications where transaction cards are not visually inspected, another dimension is added to the problem of detecting counterfeits. Specifically in that regard, it has been proposed to utilize a medium in a card that alters the orientation-frequency property of a scanning light beam in a pattern that will characterize the card, as disclosed in the referenced copending parent application, now U.S. Pat. No. 4,476,468. Such a card is not susceptible to photo-reproduction.
To consider an example, a card may modulate the polarization angle of a light beam to provide identification. Such identification is not susceptible to duplication as by photo-reproduction. Accordingly, the present invention is directed to a form of authenticator device which may be incorporated in various records, diskettes, or other structures collectively termed cards herein.
As previously proposed, orientation-frequency cards may incorporate a modulating stripe of crystals contained in a carrier medium. While such structures are effective, individual crystals normally produce very sharp discrete changes in a scanning light beam. Consequently, sensing systems for operation with such cards must be capable of high accuracy. Generally, the cost of such apparatus increases with such demands. Consequently, a need exists for transaction cards of a medium that is capable of altering an orientation-frequency property of a scanning light beam in a characteristic pattern, and in which the changes are somewhat gradual to accommodate the use of relatively low precision sensing apparatus. Additionally, a need exists for such a card that can be inexpensively produced.
Another problem attendant the use of verifiable documents, e.g. transaction cards, involves document aging. Specifically, as a document or card is carried and used over a period of time, it may become soiled, bent, scratched, marred or otherwise altered to change its effect on impinging radiation. Consequently, a need exists for a system in which the aging effects on a document are somewhat compensated or corrected.
In general, the present invention is based on recognizing the above considerations and implementing cooperative elements to afford an effective, economical, and practical document or transaction card for verification and use in combination with an effective card processing system. Particular concerns are for an economical, durable card that may be used in cooperation with apparatus of relatively low cost both for production and verification.
The disclosed embodiment, in accordance with the present invention, incorporates a document in sheet form for verification use. The document or card includes a reference medium having a random variable pattern to modulate a beam of light applied to the sheet as when the beam scans an area of the sheet. In the disclosed embodiment, the card is formed to produce a frequency-orientation characteristic pattern, e.g. stress waves, in a plastic medium, which pattern defines somewhat gradual transitions. Light modulated by the card is reduced to an analog signal unique to each specific document. The analog is quantized and converted to a digital representation. This representation is referenced on the card in a machine-readable form. With such information, the verification system tests the recorded representation with freshly observed data. Also in accordance herewith, a plurality of sensed values are combined, as in ratio relationships to somewhat cancel the effects of aging.